Method and apparatus for winding a filter element

ABSTRACT

A filter apparatus and method utilize a filter element, defining a longitudinal axis and an axial end thereof, and having a central winding structure and a length of fluted filter material wound about the winding structure with the flutes of the media oriented to provide for filtration of fluid passing axially through the filter element. An edge of filter media defines the axial end of the filter element when the media is wound about the winding structure. An axial end of the winding structure is disposed adjacent the axial end of the filter element. A winding feature extends substantially axially outward from the axial end of the winding structure to a distal end of the winding feature. The filter media is wrapped about the winding structure such that the axial end of the filter element is disposed substantially flush with the distal end of the winding feature.

FIELD OF THE INVENTION

This invention relates to fluid filters for removing particulate matterfrom a flow of fluid in liquid or gaseous form, including filters of thetype used for filtering inlet air supplied to machinery such as enginesand compressors.

BACKGROUND OF THE INVENTION

In one commonly utilized form of a filter element, the filter elementdefines a longitudinal axis and first and second axial ends of thefilter element, with the filter element including a central core, and alength of fluted filter media wound about the central core, with theflutes of the media oriented substantially longitudinal, to therebyprovide for filtration of a flow of fluid passing axially through thefilter element. Such filter elements are typically installed within ahousing, or duct, in such a manner that the filter element canperiodically be removed for cleaning or replacement with a fresh filterelement. A seal between the filter element and the housing is typicallyprovided, in such a manner that none of the fluid flowing through thehousing can bypass the filter element, to thereby ensure that all fluidpassing through the housing must enter one axial end of the filterelement and exit from the opposite axial end of the filter element.

Where possible, filter elements of the type described above aretypically formed into a right circular cylindrical shape, with thefilter media being wound about a round central core. In someapplications, however, it is necessary to form filter elements intonon-cylindrical shapes, to fit space constraints of the particularapplication. For example, in a so-called “race track shaped” element,the cross-sectional shape of the filter element is race track shaped,having a pair of curved (in some embodiments, semi-circular, ends joinedby a pair of straight segments). In such race track shaped filterelements, and in filter elements having other non-circularcross-sectional shapes, such as oval or rectangular, for example, thelength of fluted filter material is wound about a non-circular centralcore. Such non-circular central cores may have cross-sections that aresubstantially rectangular in shape.

In one prior approach to providing a race track shaped filter element,as disclosed in U.S. Pat. Nos. 7,001,450 B2; 6,746,518 B2 and 6,547,857B2, to Gieseke et al., fluted filter media is coiled about a rectangularshaped center board. The center board includes a corrugated region,which purportedly helps to hold the fluted media in place during windingof the filter element.

As is well known in the art, and stated in the patents to Gieseke,fluted filter media typically exhibits an inherent shape memory whichcan cause the media to bow outwardly, radially, away from the centerboard. In a filter element having a cylindrical central core, thisinherent curvature memory is typically not problematic, in that thecurvature of the media will not interfere with, and may actually assistin, pulling the media down onto the core, or onto a previously woundlayer of the media. For cores in race track shaped elements, however,such as the center board used in the Gieseke patent, the inherenttendency of the filter media to bow outward may make it difficult tocreate a secure, tight, seal between the first layer of the media andthe center board.

According to Gieseke, the corrugations of the center board alleviatethis problem because the fluted media is better able to mate with andengage with the corrugations of the center board than with a flatsurface. In practice, however, the corrugated section of the centerboard of Gieseke may, in fact, make it more difficult to achieve thedesired fit between the first layer of fluid media and the outer surfaceof a non-cylindrical core, by interfering with the ability of the mediato move freely while being pulled by a winding tensioning force acrossthe surface of the core during the winding operation. In addition,fluted filter media, of the type typically used in such filter elements,is fabricated from layers of paper-like material by processes which arenot amenable to accurate control of dimensional tolerances, with theresult being that, in actual practice, the fluted media may not fit wellinto the corrugations of the center board, thereby causing an additionaltendency of the first layer of media to be pushed outward away from thesurface of the center board.

As a further difficulty, the corrugations of Gieseke must be closelymatched to a given flute profile, thereby making it difficult to utilizedifferent flute spacing and shapes with a given center board, which inturn can drive up inventory and manufacturing costs. Because filterelements of this type are often disposable, so that they may be readilyreplaced at appropriate intervals, additional manufacturing complexityand cost, resulting in increase replacement cost of the element, ishighly undesirable and can be a significant detriment to successfulcompetition in the marketplace.

Because the central core, in a wound filter element, is essentially anon-operating part of the completed filter, it is desirable that thecentral core be fabricated at minimal cost, utilizing as little materialas possible, and have a configuration which can be readily manufacturedin a form that is also readily disposable or incinerable. It is alsodesirable, in some applications, that the central core be fabricated ina manner which is as light in weight as possible. The center board ofthe Gieseke patent does not meet these requirements. Although the centerboard of Gieseke includes a number of holes extending through thethickness of the center board, the center board of Gieseke includesconsiderable surplus material. This condition is exacerbated by theinclusion of the corrugated section.

The center board of Gieseke also discloses a cutout, at one end of thecenter board, to be held by a spindle during winding of the filterelement. The configuration of the cutout of Gieseke is an inefficientdrive mechanism, in that the winding torque from the spindle isapparently applied only to the sidewalls of the cutout, which arelocated closely adjacent to the winding axis and essentially formed bythe thickness of the center board. Such an inefficient drive mechanismmay make it difficult to apply sufficient winding torque, withoutdamaging the center board, to maintain a winding tension in the filtermedia which is high enough to pull the media into intimate contact withthe outer surface of the center board or previously wound layers ofmedia.

Another prior approach to forming a race track shaped filter element isshown in U.S. Pat. Nos. 7,008,467 B2 and 6,966,940 B2, to Krisko et al.Krisko uses a core construction including a race track shapednon-cylindrical, imperforate, wall member, having opposing wallsdefining an open volume within the imperforate non-cylindrical member.In cross section, the non-cylindrical member has the appearance,generally, of a flattened cylindrical-shaped tube having flat opposingside walls joined at opposite ends by curved walls, surrounding the openvolume. The opposing walls and ends of the non-cylindrical member of thecore construction of Krisko are imperforate. The core construction ofKrisko further includes structural moldings and plugs located within theopen volume, for providing strength, and axially closing off the openvolume to ensure that fluid cannot leak through the open volume insideof the non-cylindrical member.

The central core construction of Krisko is even more complex than thecenter board of Geiseke, as described above. The core construction ofKrisko also appears to include a substantial volume of excess material,making such a core construction undesirably expensive to produce andheavier than necessary. The core construction of Krisko also results ina significant amount of extra material which must be disposed of orincinerated when the filter element is replaced.

It is desirable, therefore, to provide an improved method and apparatusfor manufacturing a fluid filter element having filter media wound abouta non-cylindrical central core, in a manner which overcomes one or moreof the problems discussed above, and/or providing improved utility overthe prior art.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an improved filter apparatus and method,through utilization of a filter element having a length of filter mediawound about a winding structure which includes a winding featureextending substantially outward from an axial end of the windingstructure. The length of filter media is wrapped about the windingstructure in such a manner that the axial end of the filter element isdisposed substantially flush with a distal end of the winding feature.In some forms of the invention, the winding structure may be asubstantially open, truss-like structure.

In some forms of the invention, a filter element includes a length offilter media wound about a winding structure, with the filter elementdefining a longitudinal axis and an axial end of the filter element,when the filter media is wound about the winding structure. The windingstructure has an axial end thereof disposed adjacent the axial end ofthe filter element. The winding structure also includes a windingfeature extending substantially axially outward from the axial end ofthe winding structure to a distal end of the winding feature. The lengthof filter media is wrapped about the winding structure in such a mannerthat the axial end of the filter element is disposed substantially flushwith the distal end of the winding feature.

In some forms of the invention, the winding feature of the windingstructure may take the form of one or more lugs forming at least oneguide surface extending substantially along the width of the windingstructure, for applying a winding force to the width of the windingstructure, to thereby generate a winding moment or torque applied to thewinding structure.

In some forms of an apparatus and/or method, according to the invention,the winding feature of the winding structure may include a stop forpositioning the winding structure transversely with respect to a windingaxis.

A filter element, according to the invention, may define a longitudinalaxis and first and second axial ends of the filter element, and includea winding structure and a length of fluted filter media wound about thewinding structure with flutes of the media oriented substantiallyparallel to the longitudinal axis, to thereby provide for filtration ofa flow of fluid passing substantially parallel to the longitudinal axisthrough the filter element. The winding structure may define a windingstructure axis extending substantially parallel to the longitudinal axisof the filter element, and oppositely facing axial ends of the windingstructure disposed at opposite ends of the winding structure along thewinding structure axis adjacent the corresponding first and second axialends of the filter element. The winding structure may have a length,width and thickness thereof, with the length extending substantiallyalong the winding structure axis between the first and second axial endsof the winding structure, the width extending substantially orthogonallyto the winding structure axis, and the thickness extending substantiallyorthogonally to both the winding structure axis and the width of thewinding structure. The winding structure may also include a windingfeature extending substantially axially outward from at least one of theaxial ends of the winding structure. The winding feature is configuredfor receiving a winding torque, applied to the winding structure, forrotation of the winding structure about a winding axis extendingsubstantially parallel to the longitudinal axis of the filter element,as the media is wound onto the winding structure.

The invention may take the form of a method for constructing a filterelement, having a length of filter media wound about a windingstructure, in such a manner that the filter element defines alongitudinal axis and an axial end of the filter element, with thelength of filter media having an edge thereof which substantiallydefines the axial end of the filter element when the filter media iswound about the winding structure. The winding structure may beconfigured to have an axial end thereof disposed adjacent the axial endof the filter element, with the winding structure including a windingfeature extending substantially axially outward from the axial end ofthe winding structure to a distal end of the winding feature. The methodmay include wrapping the length of filter media about the windingstructure in such a manner that the axial end of the filter element isdisposed substantially flush with the distal end of the winding feature.

Where the winding feature of a winding structure, according to theinvention, further defines a stop for positioning the winding structuretransversely with respect to the winding axis, a method, according tothe invention, may further include using the stop of the winding featurefor transversely positioning the winding structure with respect to thewinding axis.

A method, according to the invention, may further include applying awinding torque to the winding feature for rotation of the windingstructure about a winding axis extending substantially parallel to thelongitudinal axis of the filter element, for winding the media onto thewinding structure. The method may further include engaging the windingfeature with a winding machine in a manner allowing the winding torqueto be applied to the winding feature.

Where the winding machine includes a mandrel having a driving feature,and the winding feature of the winding structure includes one or morelugs forming at least one transversely oriented guide surface foroperatively engaging the driving feature of the mandrel, a method,according to the invention, may further include operatively engaging thedriving feature of the mandrel with the transversely oriented guidesurface formed by the one or more lugs of the winding feature of thewinding frame. Where the mandrel defines a drive axis lyingsubstantially coincident with the winding axis, as the media is woundonto the winding structure, the transversely oriented guide surface anddriving features may be cooperatively configured for sliding engagementof the guide surface with the driving feature, as the winding structureis guided in a transverse direction toward the driving axis. With such astructure, a method, according to the invention, may further includeoperatively engaging the drive feature with the transversely orientedguide surface by sliding the guide surface over the driving feature to apoint where the winding axis is substantially coincident with thedriving axis. In forms of the invention where the winding feature of thewinding structure further includes a stop for engaging the drivingfeature to limit relative sliding motion between the winding structureand the mandrel, in such a manner that the winding axis is substantiallycoincident with the driving axis when the stop is substantially abuttingthe driving feature, a method, according to the invention, may furtherinclude bringing the stop into substantial abutment with the drivingfeature.

A filter apparatus and/or method, according to the invention, mayinclude a filter element, having a winding structure in the form of awinding frame, and a length of fluted filter media wound about the framewith the flutes of the media oriented substantially longitudinally, tothereby provide for filtration of a flow of fluid passing axiallythrough the filter element. In some forms of the invention, the windingframe is a substantially open, truss-like structure. Use of a windingframe, rather than the center boards or other types of cores used inprior filter elements, provides a number of advantages, including, butnot limited to improvements in manufacturability and operationalcapability and improved environmental friendliness of the filterelement.

In some forms of the invention, a filter element defines a longitudinalaxis and first and second axial ends of the filter element. A windingframe, of the filter element, defines a frame axis extendingsubstantially parallel to the longitudinal axis of the filter element,and first and second oppositely facing axial ends of the winding framedisposed at opposite ends of the winding frame along the frame axis. Thewinding frame defines a length, width and thickness thereof, with thelength extending substantially along the frame axis between the firstand second axial ends of the winding frame, the width extendingsubstantially orthogonally to the frame axis, and the thicknessextending substantially orthogonally to both the frame axis and thewidth of the winding frame. A length of fluted filter media is woundabout the winding frame with the flutes of the fluted media orientedsubstantially longitudinally to the frame axis, to thereby provide forfiltration of a flow of fluid passing substantially parallel to thelongitudinal axis through the filter element. The winding frame may besubstantially open through the thickness thereof and across the widththereof. The winding frame may also be a truss-like structure.

A winding frame, according to the invention, may include first andsecond longitudinally extending side rails joined in a transverselyspaced relationship to one another and to the frame axis by one or morecross-members extending transversely to the frame axis across the widthof the winding frame. The transversely extending cross-members may beoriented substantially perpendicular to the frame axis, or at an angleto the frame axis, or some combination thereof. The cross-members may besubstantially straight, or curved, or some combination thereof. The siderails and cross-members of the winding frame may define open areas,disposed between the side rails, and extending through the thickness ofthe frame. The side rails of the frame may be joined together by aplurality of cross-members to form a truss-like structure.

In some forms of the invention, the thickness of a winding frame,according to the invention, may have a substantially oval cross-sectiondefining a maximum sectional thickness between the side rails andconverging to lesser sectional thickness at each side rail. Thecross-section of the frame may define a substantially smooth outerperipheral surface having opposed central sections of larger radiusdisposed between the side rails, joined by straight sections to smallradius sections at the lateral edges of the frame and forming outerlongitudinally extending edges of the side rails. Where the length offluted filter media wound around the frame defines a series ofalternating peaks and valleys forming flutes, the small radius sectionsof the outer peripheral surface of the winding frame may be configuredto be closely embraced and gripped by the peaks of two or more adjacentflutes of the first layer of the filter media lying against the outerperipheral surface of the winding frame.

In some forms of the invention, a small radius section of one of theframe rails, in a winding frame according to the invention, may define aleading edge of the frame. The filter element may further include astrip of tape for joining the leading edge of the length of filtermaterial to the winding frame in such a manner that the leading edge ofthe media is attached to the frame without being substantially wrappedaround the leading edge of the frame. The leading edge of the media maybe formed by cutting the media substantially along the peak of one ofthe flutes thereof to form a resulting half-peak, and the half-peak maybe filled with an adhesive sealant.

At least one cross-member of a winding frame, according to theinvention, may be joined to the filter media, of a filter elementaccording to the invention, by a layer of adhesive/sealant, to therebypreclude fluid communication between the axial ends of the filterelement along the juncture of the media with the peripheral surface ofthe frame.

A winding frame, according to the invention, may include a cross-memberforming an axial end of the frame, and a winding feature extendingsubstantially axially outward from the axial end of the frame, with thewinding feature being configured in a manner allowing a winding torqueto be applied to the frame, for rotation of the frame about a windingaxis oriented substantially parallel with the frame axis, as the mediais wound onto the frame. The winding feature of the frame may includeone or more lugs forming at least one guide surface extendingsubstantially along the width of the winding frame, for applying awinding force to the width of the frame for generating the windingtorque. The winding feature of the frame may further define a stop forpositioning the frame transversely with respect to the winding axis.

A winding frame, according to the invention, may be configured about aparting plane extending through the width of the frame, and dividing thethickness of the frame in such a manner that the frame can be formed ina two-piece mold, having a parting line coincident with the partingplane.

The invention may also take the form of a method for constructing afilter element defining a longitudinal axis and first and second axialends of the filter element. Such a method may include wrapping a lengthof filter media about a winding frame, according to the invention.

A method, for constructing a filter element including a winding framehaving a substantially oval cross-section with small radius sections atouter edges of the winding frame, according to the invention, mayinclude attaching the leading edge of a length of media to the frame,and while applying a winding tension to the media, rotating the frameabout a winding axis through a first rotation of the frame in such amanner that the peaks of two or more adjacent flutes of a first layer ofthe filter media lying against the outer peripheral surface of thewinding frame closely embrace and grip one of the small radius sectionsof the outer peripheral surface of the frame.

Where a winding frame, according the invention, is a substantially opentruss-like structure having axial ends thereof and at least onecross-member spaced inward from the axial ends, a method, according tothe invention, may include initially applying a bead of adhesive/sealantto the cross-member spaced inward from the axial ends of the frame, andthen, after wrapping the media at least once completely about the frame,moving the bead of adhesive/sealant closer to an axial end of the frame,to thereby increase the active area of media located between the axialends of the filter element, while joining the filter media to the frameby a layer of adhesive/sealant in a manner precluding direct fluidcommunication between the axial ends of the filter element along thejuncture of the media with the frame, or between successive layers ofthe media.

A method, according to the invention, may further include applying awinding moment to the guide surface of a winding feature of a windingframe, according to the invention, in a direction substantiallyorthogonal to the frame axis and the width of the frame. The windingmoment may be applied to the guide surface of the winding feature with adriver that is rotatable about a drive axis and has one or more lugsforming at least one drive surface oriented and cooperatively configuredfor operatively engaging the guide surface of the frame. Prior towrapping the media about the frame, the driver may be engaged with theguide surface of the frame by sliding the guide surface over the drivesurface to a point where the winding axis of the frame is substantiallycoincident with the drive axis. Subsequent to wrapping the media aboutthe frame, the method may include releasing the filter element by movingthe driver axially along the drive axis away from the filter element.

Where a winding feature of a winding frame, according to the invention,includes a stop for engaging a driver, to thereby position the frameaxis substantially coincident with a drive axis of the driver when thestop is substantially abutting the driver, a method, according to theinvention, may include bringing the stop substantially into abutmentwith the driver.

A method, according to the invention, may include forming a windingframe in a two piece mold having a parting plane extending through thewidth of the winding frame and dividing the thickness of the frame insuch a manner that the frame has a parting line coincident with theparting plane.

Other aspects, objectives and advantages of the invention will beapparent from the following detailed description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification illustrate several aspects of the present invention and,together with the description, serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a perspective illustration of an exemplary embodiment of afilter element, according to the invention having a length of flutedfilter media wrapped about a winding structure in the form of a windingframe;

FIGS. 2-5 are orthographic views of the winding frame of the exemplaryembodiment of the filter element shown in FIG. 1;

FIG. 6 is a perspective view of an exemplary embodiment of a windingfeature of the winding frame shown in the exemplary embodiment of thefilter element of FIG. 1;

FIGS. 7 and 8 are alternate embodiments of a winding feature, inaccordance with the invention, of a winding structure according theinvention;

FIGS. 9-11 are illustrations of the attachment of leading and trailingedges of the filter media to a leading edge and a trailing edge,respectively, of the winding frame in the exemplary embodiment of thefilter element shown in FIG. 1;

FIG. 12 is a perspective illustration of details of construction of theexemplary embodiment of the filter element shown in FIG. 1;

FIG. 13 is a rolled-out illustration of the manner of applying a bead ofadhesive/sealant during construction of the exemplary embodiment of thefilter element shown in FIG. 1; and

FIG. 14 is a alternate embodiment of an apparatus for constructing theexemplary embodiment of the filter element shown in FIG. 1.

While the invention will be described in connection with certainpreferred embodiments, there is no intent to limit it to thoseembodiments. On the contrary, the intent is to cover all alternatives,modifications and equivalents as included within the spirit and scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a first exemplary embodiment of the invention in the formof a filter element 100 defining a longitudinal axis 102 and first andsecond axial ends 104, 106 of the filter element 100. The exemplaryembodiment of the filter element 100 includes a winding structure, inthe form of a winding frame 108, and a length of fluted filter media 110wound about the frame 108, with the flutes of the fluted filter mediabeing oriented substantially longitudinally to the longitudinal axis ofthe filter element 100, to thereby provide for filtration of a flow offluid passing axially through the filter element 100.

As shown in FIGS. 1-7, and described in more detail below, the windingframe 108 of the exemplary embodiment 100 of the filter element is asubstantially open, truss-like structure, having a smooth advantageouslyshaped outer periphery, allowing the media 110 to be effectively pulledinto intimate contact with the outer periphery of the winding frame 100by a winding tension force applied to the media 110, during constructionof the filter element 100. The frame 108 also includes a pair of windingfeatures 112, extending substantially axially outward from oppositeaxial ends of the frame 108, and configured in a manner allowing awinding torque to be applied to the frame 108, for rotation of the frameabout a winding axis extending substantially parallel to thelongitudinal axis 102 of the filter element, as the media 110 is woundonto the frame 108. As will be understood from the detailed descriptionbelow, the winding features 112 of the winding frame 108 of theexemplary embodiment of the filter element 100 are configured tointerface with a driver element of a winding machine in a mannerfacilitating attachment and alignment of the winding frame 108 with thedriver, and for allowing a winding torque from the driver to betransmitted more efficiently and effectively to the winding frame 108then was achievable with the center boards and core constructions ofprior filter elements.

As shown in FIGS. 9-14, and described in greater detail below, a leadingedge 114 of the length of fluted filter media 110 is joined to a leadingedge 116 of the winding frame 108 by a length of securing tape 118. Theleading edge 114 of the fluted filter media 110 is cut on a peak 120 ofthe fluted media 110, to create a half peak 122 of the media 110 openingoutward toward the leading edge 114 of the media. The half peak 122 isfilled with a bead of adhesive sealant 124, to preclude leakage of fluidlongitudinally through the half peak 122 from the first to the secondaxial ends 104, 106 of the filter element 100. The filter media 110 isfurther secured and sealed to the frame 108, and between successivelayers of the filter media 110 by an additional bead of adhesive/sealant126, applied in a manner described in more detail below.

As will be understood, by those having skill in the art, utilization ofa winding frame, in accordance with the invention, for constructing afilter element, provide significant advantages over the prior art, forfabricating a filter element in an efficient and effective mannerwithout resorting to counter-productive machinations, such as thecorrugated bearing surface of the center board or complex coreconstructions utilized in the prior art.

It is contemplated that, in practicing the invention, fluted filtermedia of conventional construction, as described, for example, in U.S.Pat. No. 3,025,963 to Bauer, unconventional fluted filter media of thetype described in commonly assigned U.S. patent applications Ser. No.10/979,390 to Driml, et al., and Ser. No. 10/979,453 to Merritt, et al.,for example, or any other appropriate type of fluted filter media, maybe utilized, with the disclosure and teachings of the aforementionedpatent to Bauer and applications to Driml and Merritt being incorporatedherein in their entireties by reference.

As shown in FIGS. 2-4, the winding frame 108 defines a frame axis 128extending substantially parallel to the longitudinal axis 102 of thefilter element 100. The frame 108 further defines first and secondoppositely facing axial ends 130, 132 of the winding frame 108, disposedat opposite ends of the winding frame 108 along the frame axis 128. Thewinding frame 108 further defines a length “L”, width “W” and thickness“T” of the winding frame 108, with the length L extending substantiallyalong the frame axis 128 between the first and second axial ends 130,132 of the frame 108, the width W extending substantially orthogonallyto the frame axis 128, and the thickness T extending substantiallyorthogonally to both the frame axis 128 and the width W of the windingframe 108.

The winding frame 108, of the exemplary embodiment of the filter element100, includes first and second longitudinally extending side rails 134,136, joined in a transversely spaced relationship to one another and theframe axis 128 by a plurality of cross members 138-140, 143, 144, 146,148, 150, extending transversely to the frame axis 128 across the widthW of the winding frame 108. As shown in FIG. 2, several of the crossmembers 138, 139, 140, 142, 143, extend generally perpendicularly to theside rails 134, 136 and frame axis 128. Other cross members 144, 146,148, 150, extend transversely between the first and second side rails134, 136 in an angular relationship to the side rails 134, 136 and frameaxis 128.

As will be appreciated, from an examination of FIG. 2, the arrangementof the side rails 134, 136 and cross-members 138, 139, 140, 142, 143,144, 146, 148, 150, are joined together to form a truss-like structuredefining a plurality of open areas 152 disposed between the side rails134, 136 and extending through the thickness T of the frame 108. Thetruss-like structure of the frame 108 provides for a very efficient andeffective use of the material, from which the frame 108 is fabricated,in a manner providing a structure which is significantly lighter inweight than the center boards or core constructions of prior filterelements, to thereby reduce manufacturing costs providing betterutilization of scarce natural resources, and also providing a structurewhich is more amenable to recycling and incineration than the centerboards and core constructions of prior filter elements.

As shown in FIGS. 3 and 5, the frame thickness T has a substantiallyoval cross section, having a maximum sectional thickness between theside rails 134, 136 and converging to a lesser sectional thickness ateach side rail 134, 136. The cross section of the frame 108 defines asubstantially smooth outer peripheral surface 154 having opposed centralsections 156 of larger radius “R” disposed between the side rails 134,136, joined by straight sections 158 to small radius “r” sections 160forming outer longitudinally extending edges of the side rails 134, 136.

As shown in FIGS. 9 and 12, one of the edges 160 of the frame 108 formsthe leading edge 116 of the frame 108, and the other edge 160 of theframe 108 forms a trailing edge 117 of the frame 108. When joining themedia 110 to the frame 108 with the tape 118, the leading edges 114, 116of the media 110 and frame 108 are positioned at a selected spaceddistance “d”, prior to joining the media 110 to the frame with the tape118, with the particular spaced distance d being selected in such amanner that the leading edge 114 of the media 110 is brought intocontact with the outer peripheral surface 154 of the frame 108 withoutthe media 110 being wrapped around the leading edge 160 of the frame108, as the frame 108 is rotated about a winding axis substantiallycoincident with the frame axis 128 and longitudinal axis 102 of thefilter element 100. Specifically, as shown in FIG. 10, it is preferredthat the spacing d between the leading edges 114, 116 of the media 110and frame 108 be such that the tape 118 wraps around the edge 160 of theframe in a manner allowing the leading edge 114 of the media 110 to comeinto contact with the outer peripheral surface 154 of the frame 108along the straight section 158 or the large radius curve section 154 ofthe frame 108. By virtue of this arrangement, the need for bending themedia 110 around the leading edge 116 of the frame is eliminated, withthe tape 118 providing a secure attachment of the media to the frame insuch a manner that a relatively high winding tensile force F_(T) may beapplied to the media 110 during the winding operation, in order toensure that the media 110 is pulled into intimate contact with thewinding frame 108 as the first layer of media 110 is applied, and intointimate contact with a previously wound layer of media 110 as thewinding process continues.

As shown in FIG. 12, in the exemplary embodiment of the filter elementdescribed herein, the filter media 110 includes an undulating sheet 162of porous filter material joined to a backing sheet 164. The spacesbetween the undulating sheet 162 and backing sheet 164 at the end of thelength of filter media 110 adjacent the first end 104 of the filterelement and leading edge 116 of the winding frame 108 are filled with abead of adhesive/sealant 166, as indicated by dashed lines in FIG. 12,in the manner known in the art.

As shown in FIGS. 11-13, as the media 110 is wound onto the frame 108, asecond bead of adhesive 126 is applied adjacent the second end 106 ofthe filter element 108 and 112 of the frame, in such a manner thatflutes of the filter media 110 which are not sealed by the bead ofadhesive 166 at the first end 104 of the filter are sealed by the secondbead of adhesive 126 adjacent the second end of the filter element 100.As is well understood in the art, by virtue of this arrangement,adjacent flutes of the filter media 110 are blocked at opposite endsthereof by the first and second beads of adhesive sealant 166, 162 insuch a manner that fluid entering one of the ends 104, 106 of the filterelement must pass through the porous filter material of the undulatingsheet 162, or the backing sheet 164 where the backing sheet is also madeof porous filter material, into an adjacent flute in order to exit thefilter element 100 at the opposite end 104, 106 thereof. In passingthrough the porous filter material in this manner, particulate matter isremoved from the fluid and trapped within the filter media 110.

As shown in FIGS. 2, 12 and 13, one cross member 139 of the frame 108 isspaced inward from the second axial end 132, and is adapted forreceiving the bead 126 of adhesive sealant during the first revolutionof the frame 108, as the first layer of media 110 is being wound ontothe frame 108. As indicated in FIG. 9, and in the rolled-out view ofFIG. 13, the bead 126 of adhesive sealant is applied by an applicator168.

As shown in FIGS. 11-14, in the exemplary embodiment 100, the applicator168 is initially positioned at a distance from the second end of theframe 108 substantially equal to the distance at which the cross member139 is spaced from the second end 132. The applicator 168 beginsdispensing the bead 126 of adhesive/sealant onto the cross member 139,adjacent the trailing edge 117 of the winding frame 108, as shown inFIG. 13, at a first axial location 170, as indicated in FIG. 13. Theapplicator 168 then moves longitudinally across the frame 108 and alongthe media 110 a distance 2W, which is substantially equal to twice thewidth W of the frame 108, while continuing to dispense the bead ofadhesive/sealant 126. In this manner, the bead of adhesive/sealant 126is initially applied across the cross member 139 of the frame 108, insuch a manner that a double-thick bead of adhesive/sealant is appliedalong the upper side (as shown in FIGS. 11-14) of the cross member 139of the frame 108, and a single bead of adhesive sealant is applied alongthe lower side (as oriented in FIGS. 11-14) of the cross member 139 ofthe frame 108, as the frame 108 is rotated about the frame axis 128 tobegin winding the media 110 onto the frame 108.

As indicated in FIG. 13, after wrapping the media 110 at least oncecompletely about the frame 108, the applicator 168 moves axially towarda second axial position 172 in such a manner that the bead of sealant126 substantially traces a pattern, shown in the rolled-out view of FIG.13, onto the media 110.

This approach to applying the bead of sealant 126 is utilized inrecognition of the fact that it is difficult to control the flow ofadhesive sealant 126 through the applicator 168 from the moment that theflow of adhesive sealant 126 is initiated. By initially applying thebead of adhesive sealant 126 to the cross member 139, rather thanattempting to apply it initially to the cross member 138 of the frame108, the initial uncertainty in the flow rate of the adhesive sealant126 through the applicator 168 need not be reckoned with further, inorder to ensure that the adhesive sealant 126 is not squeezed out of thesecond end 104 of the filter element between layers of media 110 in amanner that might lead to plugging the open flutes at the second end 106of the filter element 100. It is desirable, however, to have the secondbead of adhesive sealant 126 be primarily located at a second axialposition as near as possible to the second end 106 of the filter element100 to maximize the length of the flutes in the filter element availablefor passage through the walls thereof of the fluid as it traverses thefilter element from one end to the other thereof.

It will be understood, by those having skill in the art, that in otherembodiments of the invention, in practicing the invention, the bead ofadhesive/sealant 126 may be applied using alternate techniques andapparatuses, consistent with the configuration and desired resultsdescribed herein. For example, as shown in FIG. 9, in alternateembodiments of the invention, the applicator 168 can alternatively beinitially positioned above the tape 118, rather than above the crossmember 139, at a distance from the second end of the frame 108substantially equal to the distance at which the cross member 139 isspaced from the second end 132. The applicator 168 may then begindispensing the bead 126 of adhesive/sealant onto the tape 118, as shownin FIG. 9, and continue dispensing the bead of adhesive/sealant 126 asthe frame 108 is rotated about the frame axis 128. In this manner, thebead of adhesive sealant 126 is initially applied across the crossmember 139 of the frame 108, as the cross member 139 is brought intocontact with the bead of adhesive sealant 126 previously deposited ontothe tape 118 and/or the surface of the media 110, as the frame 108 isrotated about the frame axis 128 to begin winding the media 110 onto theframe 108. The position of the applicator 168 may also be movedtransversely and/or longitudinally, in a manner similar to that shown inFIG. 13, to move the location of the bead of adhesive/sealant 126 closerto the second end 106 of the filter element 100, as described above inrelation to the exemplary embodiment 100.

As shown in FIG. 11, it is desirable to have the contour of the trailingedge 117 of the frame 108 be configured in such a manner, that as themedia 110 is wrapped under winding tension F_(T) around the frame 108,the peaks 120 of two or more adjacent flutes of a first layer of thefilter media 110 are tightly pulled against the outer peripheral surface154 of the winding frame 108 in such a manner that the media 110 closelyembraces and essentially grips the small radius section 160 at thetrailing edge 117 of the frame 108. In this regard, it is desirable tohave the particular configuration of the edge 160 of the winding frame108 coordinated with the pitch spacing of the peaks 120 of the media110, in such a manner that the media 110 can be pulled down intointimate contact with the outer peripheral surface 154 of the frame 108during application of the first winding layer.

It will be noted, by those having skill in the art, that, by virtue ofthe fact that the tape 118 at the leading edge 116 of the frame 108 isvery thin in comparison to the thickness of the media 110, as the media110 is further wrapped over the tape 118 at the leading edge 116 of theframe, the second layer of media 110 will lay very tightly and neatlyagainst the outer surface of the first layer of media 110. It will befurther noted, that by beginning the feed of adhesive sealant 126 ontothe surface of the tape 118 in the distance d between the leading edges114, 116 of the media and the frame 108, any excess amount of adhesivesealant 126 initially expressed by the applicator 168 will spreadlongitudinally along the side rail (134 or 136) forming the leading edge116 of the frame 108 in a manner creating a smooth transition betweenthe tape 118 and the leading edge 114 of the media 110 as it is wrappedonto, and pulled tight against, the outer peripheral surface 154 of thewinding frame 108.

Those having skill in the art will recognize that, by virtue of thearrangement described above, the media 110 may be pulled along thesmooth outer peripheral surface 154 of the winding frame 108 in asliding motion leading to a significantly tighter fit between the mediaand the winding frame 108 than can typically be achieved in prior filterelements having other types of center boards and/or core constructions,and in particular a tighter fit than can be achieved by those centerboards having varying areas including corrugated or other surfacetreatments to engage the flutes of the filter media being used to formthe filter element. It will yet further be recognized, that the methodof attachment of the leading edge 114 of the filter media to the leadingedge 116 of the frame with the longitudinally oriented strip of tape118, particularly in combination with the manner in which the media iscaused to closely embrace and grip the trailing edge 117 of the frame108 that the attachment between the filter media 110 and frame 108 thatis achieved through practice of the present invention provides asubstantially stronger attachment than is achieved in prior filterelements, such that a higher winding tensile force F_(T) may be utilizedin forming a filter element, according to the invention, thereby furtherfacilitating construction of a filter element 100, according to theinvention.

As best shown in FIGS. 2, 3 and 6, the winding features 112, of thewinding frame 108 of the exemplary embodiment of the filter element 100,extend substantially axially outward from cross members 138, 143respectively forming the first and second axial ends 130, 132 of theframe 108. The winding features 112 at the first and second axial ends130, 132 of the frame 108 are essentially identical but face in oppositeaxial directions. Accordingly, the winding feature 112 at the second endof the frame 108 will be specifically described, but it is understoodthat the winding feature 112 at the first end 130 of the frame 108 is ofsubstantially identical configuration. It will be noted, however, thatin other embodiments of the invention, winding features at opposite endsof the frame need not be identical, that a winding feature may beprovided at only an axial end of the frame.

The winding feature 112 at the second end 138 of the frame 108, as shownin FIGS. 2-4 and 6, is formed by a plurality of lugs which, incombination define a pair of guide surfaces 178, 180 extendingsubstantially along the width W of the frame 108 in a manner allowingthe guide surfaces 178, 180 to slide over corresponding driving surfaces181, 182 of a pair of drivers 184 of a winding machine (not shown) forapplying a driving torque through the drivers 184 to the frame 108 in amanner generating a winding moment to the guide surfaces 178, 180directed substantially orthogonally to the frame axis 128 and the widthW of the frame 108, as indicated by arrows M_(W) in FIGS. 3 and 12. Byapplying the winding moment M_(W) in this manner across the width W ofthe frame rather than substantially across the thickness of the frame asin prior art filters having a notched center board, a higher windingmoment and resulting winding torque can be utilized for winding themedia 110 onto the frame 108, which thereby causes a higher windingtensile force F_(T) to be utilizable to facilitate construction of thefilter element 100. As shown in FIGS. 3 and 6, one of the lugs 176 ofthe winding feature 112 of the exemplary embodiment of the winding frame108 is further configured to define a stop 186 for engaging the drivers184, to thereby position the frame axis 128 substantially coincidentwith the drive axis 185 when the stop 186 is substantially abutting thedriver 184.

As will be understood, by those having skill in the art, a drivingfeature 112, according to the invention, may take a variety of forms,within the scope of the invention, other than the one described above inrelation to the exemplary embodiment of the filter element 100. Forexample, fewer or more lugs may be utilized for forming the windingfeature, in the manner illustrated in FIGS. 7 and 8 which show twoalternate embodiments. It will also be appreciated that a windingelement, according to the invention, and methods for forming and/orutilizing a winding element according to the invention, may also be usedin core structure other than the frame-like core 108 described hereinwith regard to the exemplary embodiment of the filter element 100.

The particular embodiment of the winding feature 112 selected for theexemplary embodiment shown in FIGS. 1-6 was selected because it providesthe advantage of allowing the winding frame 108 to be formed in a twopiece mold (not shown) having a parting plane 188 extending through thewidth W of the frame 108 to effectively divide the thickness T of theframe 108 in such a manner that the frame 108 has a parting line 190coincident with the parting plane 188. In this manner, the embodimentshown in FIG. 6 is more readily moldable, utilizing only a two-piecemold, then the embodiment shown in FIGS. 7 and 8 which would require amold having additional pieces to form the winding features asillustrated in FIGS. 7 and 8.

As shown in FIG. 14, it may be desirable, in some embodiments of theinvention, to have the drivers 184 include notches 191 therein,corresponding to the particular configuration of the winding feature112, in such a manner that the winding frame 108 need not be movedslidably as far in a lateral direction to engage the drivers 184 andposition the frame 108 with respect to the drive axis 185. As furthershown in FIG. 14, it may be desirable to provide some sort of rotatableguide 200 at each end of the filter element 100, perhaps as part of awinding mandrel assembly (not shown), in order to facilitate guidance ofthe media 110 onto the frame 108 during construction of the filterelement 100.

In the exemplary embodiment of the filter element 100, it will be notedthat the media 110 has a lateral width, in the direction of thelongitudinal axis 102 of the filter element 100, which extends beyondthe first and second ends 130, 132 of the frame 108, with the distalends of the lugs 176 of the winding features 112 being disposedsubstantially flush with the lateral edges of the filter media 110 atthe axial ends 104, 106 of the filter element. By virtue of thisarrangement, the volume of active filter media 110 is maximized, for agiven axial length of the filter element 100. With this arrangement,however, it is not possible to slide the completed filter element 100off of the drivers 184 in a direction opposite to that in which theframe 108 was slidingly installed onto the drivers 184 prior to windingthe filter media 110 around the frame 108. It is contemplated thereforethat, in accordance with a method for practicing the invention,subsequent to wrapping the media 110 about the frame 108, the filterelement 100 is released from the drivers 184 by moving one or both ofthe drivers 184 axially along the drive axis 185 away from the filterelement 100.

Although the exemplary embodiments described hereinabove, andspecifically illustrated in the accompanying drawing figures, show awinding structure, in accordance with the invention, in the form of thewinding frame 108, those having skill in the art will recognize that theinvention may also be practiced with other forms of winding structureshaving configurations that do not include one or all of the open areas152 but still having a winding feature 112, in accordance with theinvention.

All references, including publications, patent applications, and patentscited herein are hereby incorporated by reference to the same extent asif each reference were individually and specifically indicated to beincorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) is to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A method for constructing a filter element, having a length of filtermedia wound about a winding structure, wherein, the filter elementdefines a longitudinal axis and an axial end of the filter element, thelength of filter media has an edge of the filter media whichsubstantially defines the axial end of the filter element when thefilter media is wound about the winding structure, the winding structurehas an axial end thereof disposed adjacent the axial end of the filterelement, and the winding structure includes a winding feature extendingsubstantially axially outward from the axial end of the windingstructure to a distal end of the winding feature, the method comprising,wrapping the length of filter media about the winding structure in sucha manner that the axial end of the filter element is disposedsubstantially flush with the distal end of the winding feature.
 2. Themethod of claim 1, wherein, the winding feature of the winding structurefurther defines a stop for positioning the winding structuretransversely with respect to the winding axis, and the method furthercomprises, using the stop of the winding feature for transverselypositioning the winding structure with respect to the winding axis. 3.The method of claim 1, further comprising, applying a winding torque tothe winding feature for rotation of the winding structure about awinding axis extending substantially parallel to the longitudinal axisof the filter element, for winding the media onto the winding structure.4. The method of claim 3, further comprising engaging the windingfeature with a winding machine in a manner allowing the winding torqueto be applied to the winding feature.
 5. The method of claim 4, wherein,the winding machine includes a mandrel having a driving feature, thewinding feature comprises, one or more lugs forming at least onetransversely oriented guide surface for operatively engaging the drivingfeature of the mandrel, and the method further comprises, operativelyengaging the driving feature of the mandrel with the transverselyoriented guide surface formed by the one or more lugs of the windingfeature of the winding frame.
 6. The method of claim 5, wherein, themandrel defines a drive axis lying substantially coincident with thewinding axis as the media is wound onto the winding structure, thetransversely oriented guide surface and driving feature arecooperatively configured for sliding engagement of the guide surfacewith the driving feature as the winding structure is guided in atransverse direction toward the driving axis, and the method furthercomprises, operatively engaging the driving feature with thetransversely oriented guide surface by sliding the guide surface overthe driving feature to a point where the winding axis is substantiallycoincident with the driving axis.
 7. The method of claim 6, wherein, thewinding feature of the winding structure further defines a stop forengaging the driving feature to limit relative sliding motion betweenthe winding structure and the mandrel in such a manner that the windingaxis is substantially coincident with the driving axis when the stop issubstantially abutting the driving feature, and the method furthercomprises, bringing the stop into substantial abutment with the drivingfeature.
 8. A filter element, comprising, a length of filter media woundabout a winding structure, wherein, the filter element defines alongitudinal axis and an axial end of the filter element, the length offilter media has an edge of the filter media which substantially definesthe axial end of the filter element when the filter media is wound aboutthe winding structure, the winding structure has an axial end thereofdisposed adjacent the axial end of the filter element, the windingstructure includes a winding feature extending substantially axiallyoutward from the axial end of the winding structure to a distal end ofthe winding feature, and the length of filter media is wrapped about thewinding structure in such a manner that the axial end of the filterelement is disposed substantially flush with the distal end of thewinding feature.
 9. The filter element of claim 8, wherein, the windingfeature of the winding structure comprises, one or more lugs forming atleast one guide surface extending substantially along the width of thewinding structure, for applying a winding force to the width of thewinding structure for generating a winding torque applied to the windingstructure.
 10. The filter element of claim 9, wherein, the windingfeature of the winding structure further defines a stop for positioningthe winding structure transversely with respect to the winding axis. 11.A filter element defining a longitudinal axis and first and second axialends of the filter element, the filter element comprising: a windingstructure, and a length of fluted filter media wound about the windingstructure with the flutes of the media oriented substantially parallelto the longitudinal axis, to thereby provide for filtration of a flow offluid passing substantially parallel to the longitudinal axis throughthe filter element; the winding structure defining a winding structureaxis extending substantially parallel to the longitudinal axis of thefilter element, and oppositely facing axial ends of the windingstructure disposed at opposite ends of the winding structure along thewinding structure axis adjacent the corresponding first and second axialends of the filter element; the winding structure having a length, widthand thickness thereof, with the length extending substantially along thewinding structure axis between the first and second axial ends of thewinding structure, the width extending substantially orthogonally to thewinding structure axis, and the thickness extending substantiallyorthogonally to both the winding structure axis and the width of thewinding structure; the winding structure also including a windingfeature extending substantially axially outward from at least one of theaxial ends of the winding structure; the winding feature beingconfigured for receiving a winding torque, applied to the windingstructure, for rotation of the winding structure about a winding axisextending substantially parallel to the longitudinal axis of the filterelement, as the media is wound onto the winding structure.
 12. Thefilter element of claim 11, wherein, the winding structure defines firstand second oppositely facing axial ends thereof, and the filter elementfurther comprises, a winding feature extending substantially axiallyoutward from each of the first and second axial ends of the windingstructure.
 13. The filter element of claim 11, wherein, the windingstructure defines a body thereof having first and second longitudinallyextending edges thereof joined in a transversely spaced relationship toone another and the winding structure axis.
 14. The filter element ofclaim 13, wherein the winding structure thickness has a substantiallyoval cross section, having a maximum sectional thickness between theedges and converging to a lesser sectional thickness at each edge. 15.The filter element of claim 14, wherein the cross section defines asubstantially smooth outer peripheral surface having opposed centralsections of large radius disposed between the edges, joined by straightsections to small radius sections forming outer longitudinally extendingsurfaces of the edges.
 16. The filter element of claim 15, wherein,winding structure is joined to the filter media by a layer ofadhesive/sealant, to thereby preclude fluid communication between theaxial ends of the filter element along the juncture of the media withthe peripheral surface of the winding structure.
 17. The filter elementof claim 15, wherein, the length of fluted filter media defines a seriesof alternating peaks and valleys forming the flutes, and the smallradius sections of the outer peripheral surface of the winding structureare configured to be closely embraced and gripped by the peaks of two ormore adjacent flutes of a first layer of the filter media lying againstthe small radius sections of the outer peripheral surface of the windingstructure.
 18. The filter element of claim 17, wherein, the length offilter media defines a leading edge thereof, the small radius section ofone of edges defines a leading edge of the winding structure, and thefilter element further comprises a strip of tape for joining the leadingedge to the winding structure in such a manner that the leading edge ofthe media is attached to the winding structure without beingsubstantially wrapped around the leading edge of the winding structure.19. The filter element of claim 18, wherein, the leading edge of themedia is formed by cutting the media substantially along one of thepeaks thereof, to form a resulting half-peak, and the half peak isfilled with an adhesive sealant.
 20. The filter element of claim 11,wherein, the winding feature of the winding structure comprises, one ormore lugs forming at least one guide surface extending substantiallyalong the width of the winding structure, for applying a winding forceto the width of the winding structure for generating the winding torque.21. The filter element of claim 20, wherein, the winding feature of thewinding structure further defines a stop for positioning the frametransversely with respect to the winding axis.
 22. The filter element ofclaim 21, wherein, the winding structure is configured about a partingplane extending through the width of the winding structure, and dividingthe thickness of the winding structure in such a manner that the windingstructure can be formed in a two-piece mold having a parting linecoincident with the parting plane.
 23. The filter element of claim 11,wherein, the winding structure comprises a winding frame having firstand second longitudinally extending side rails joined in a transverselyspaced relationship to one another and to the longitudinal axis by oneor more cross-members extending transversely to the longitudinal axis.24. The filter element of claim 23, wherein, the winding frame issubstantially open through the thickness of the winding structure andacross the width of the winding structure.